clover/docs/en/gpio.md

Working with GPIO

GPIO (General-Purpose Input/Output) – is a type of Raspberry Pi's pins, with programmatically adjustable and measurable voltage. On some of the pins there also is hardware implemented PWM.

Info Use the pinout for figuring out, which Raspberry Pi's pins support GPIO and PWM.

The RPi image includes pigpio library for work with GPIO. To interact with this library, run the appropriate daemon:

sudo systemctl start pigpiod.service

For enabling automatic launch of the daemon, use command:

sudo systemctl enable pigpiod.service

Example of working with the library:

import time
import pigpio

# initializing connection to pigpiod
pi = pigpio.pi()

# setting pin 11 mode for output
pi.set_mode(11, pigpio.OUTPUT)

# enabling signal of pin 11
pi.write(11, 1)

time.sleep(2)

# disabling signal on pin 11
pi.write(11, 0)

# ...

# setting pin 12 mode for input
pi.set_mode(12, pigpio.INPUT)

# read the state of pin 12
level = pi.read(12)

For finding out pins' numbers, use the Raspberry Pi pinout.

Connecting servos

Most of servos are controlled with PWM signal. Extreme positions of servos are reached with signal widths approximately equal to 1000 and 2000 µs. Values for a specific servo can be determined experimentally.

Connect the signal wire of the servo to one of GPIO-pins of the Raspberry. For controlling a servo, connected to the pin 13, use a code like this:

import time
import pigpio

pi = pigpio.pi()

# setting mode of pin 13 to output
pi.set_mode(13, pigpio.OUTPUT)

# setting pin 13 to output PWM signal 1000 us
pi.set_servo_pulsewidth(13, 1000)

time.sleep(2)

# setting pin 13 to output PWM signal 2000 us
pi.set_servo_pulsewidth(13, 2000)

Connecting electromagnet

For connecting an electromagnet, use a field-effect transistor (MOSFET). Connect the MOSFET to one of GPIO-pins of the Raspberry Pi. For controlling the magnet, connected to the pin 15, use a code like this:

import time
import pigpio

pi = pigpio.pi()

# setting mode of pin 15 for output
pi.set_mode(15, pigpio.OUTPUT)

# enabling the magnet
pi.write(15, 1)

time.sleep(2)

# disabling the magnet
pi.write(15, 0)